John S. Wilkie

A high affinity antiserum specific for the ecdysone nucleus

Abstract The 22-hemisuccinate ester of α-ecdysone was conjugated to bovine thyroglobulin and used to raise an antiserum which has a greater affinity for α-ecdysone and an overall higher sensitivity than those antisera previously reported. Modification of the tetracyclic nucleus characteristic of the ecdysones by either hydroxylation or dehydroxylation appreciably diminishes the ability of the ecdysone to compete for the antibody binding sites. Deviations from the side chain structure of α-ecdysone also reduce the affinity of such molecules (e.g. β-ecdysone, ponasterone A and inokosterone) but to a significantly lesser degree than alteration of the tetracyclic nucleus.

Functionalised polysiloxanes as injectable, in situ curable accommodating intraocular lenses.

The aged eyes ability to change focus (accommodation) may be restored by replacing the hardened natural lens with a soft gel. Functionalised polysiloxane macromonomers, designed for application as an injectable, in situ curable accommodating intraocular lens (A-IOL), were prepared via a two-step synthesis. Prepolymers were synthesised via ring opening polymerisation (ROP) of octamethylcyclotetrasiloxane (D(4)) and 2,4,6,8-tetramethylcyclotetrasiloxane (D(4)(H)) in toluene using trifluoromethanesulfonic acid (TfOH) as catalyst. Hexaethyldisiloxane (HEDS) was used as the end group to control the molecular weight of the prepolymers, which were then converted to macromonomers by hydrosilylation of the SiH groups with allyl methacrylate (AM) to introduce polymerisable groups. The resulting macromonomers had an injectable consistency and thus, were able to be injected into and refill the empty lens capsular bag. The macromonomers also contained a low ratio of polymerisable groups so that they may be cured on demand, in situ, under irradiation of blue light, in the presence of a photo-initiator, to form a soft polysiloxane gel (an intraocular lens) in the eye. The pre-cure viscosity and post-cure modulus of the polysiloxanes, which are crucial factors for an injectable, in situ curable A-IOL application, were controlled by adjusting the end group and D(4)(H) concentrations, respectively, in the ROP. The macromonomers were fully cured within 5 min under light irradiation, as shown by the rapid change in modulus monitored by photo-rheology. Ex vivo primate lens stretching experiments on an Ex Vivo Accommodation Simulator (EVAS) showed that the polysiloxane gel refilled lenses achieved over 60% of the accommodation amplitude of the natural lens. An in vivo biocompatibility study in rabbits using the lens refilling (Phaco-Ersatz) procedure demonstrated that the soft gels had good biocompatibility with the ocular tissue. The polysiloxane macromonomers meet the targeted optical and mechanical properties of a young natural crystalline lens and show promise as candidate materials for use as injectable, in situ curable A-IOLs for lens refilling procedures.

The use of corneal organ culture in biocompatibility studies

This study investigated the potential of a corneal organ culture system in the evaluation of polymers for ophthalmic devices that require epithelialisation. Two different polymers were tested in lenticule form to explore the sensitivity of this in vitro assay. Polycarbonate and perfluoropolyether-based lenticules were surgically implanted into bovine corneas and compared with a parallel series of sham-wounded corneas. Following surgery, all corneas were maintained in an air/liquid organ culture system for up to 8 days during which time they were evaluated clinically to monitor the rate of epithelial growth across the lenticule surface (implanted) or wound bed (sham). Data showed differences in the kinetics of epithelial migration according to the underlying surface with full epithelialisation of the sham series occurring on day 5+/-0.5, the perfluoropolyether lenticules on day 6+0.5 and polycarbonate lenticules on day 8+/-0.5. Histology revealed differences in the structure and morphology of the migrating and stable epithelium in each series of corneas. The differential response of the corneal epithelium was related to the physiochemical characteristics of the natural (sham) or synthetic (perfluoropolyether or polycarbonate) substrata which the epithelium could detect when maintained in organ culture. This assay system has utility for screening candidate polymers for certain ophthalmic applications.

Blechnosides A and B: ecdysteroid glycosides from Blechnum minus

Abstract The structures of two new ecdysteroid glycosides from Blechnum minus have been shown, on the basis of chemical, mass spectral, 1 H NMR and 13 CNMR spectral evidence, to be 2-deoxyecdysone 3-β- d -glycopyranoside (blechnoside A) and 2-deoxyecdysone 25-β- d -glucopyranoside (blechnoside B).

The influence of surface topography of a porous perfluoropolyether polymer on corneal epithelial tissue growth and adhesion

Design principles for corneal implants are challenging and include permeability which inherently involves pore openings on the polymer surface. These topographical cues can be significant to a successful clinical outcome where a stratified epithelium is needed over the device surface, such as with a corneal onlay or corneal repair material. The impact of polymer surface topography on the growth and adhesion of corneal epithelial tissue was assessed using porous perfluoropolyether membranes with a range of surface topography. Surfaces were characterised by AFM and XPS, and the permeability and water content of membranes was measured. Biological testing of membranes involved a 21-day in vitro tissue assay to evaluate migration, stratification and adhesion of corneal epithelium. Similar parameters were monitored in vivo by surgically implanting membranes into feline corneas for up to 5 months. Data showed optimal growth and adhesion of epithelial tissue in vitro when polymer surface features were below a 150 nm RMS value. Normal processes of tissue growth and adhesion were disrupted when RMS values approached 300 nm. Data from the in vivo study confirmed these findings. Together, outcomes demonstrated the importance of surface topography in the design of implantable devices that depend on functional epithelial cover.

Preparation of bicyclic herbicide precursors by intramolecular stork-danheiser kinetic alkylation reactions of methyl 1-(haloalkyl)-3-methoxy-5-oxocyclohex-3-ene-1-carboxylate derivatives

Reductive alkylation of methyl 3,5-dimethoxybenzoate with the dibromoalkane and the bromochloroalkane derivatives (4a-d) and (4e-g) afforded, after acid hydrolysis, the corresponding methyl 1-( haloalkyl )-3-methoxy-5-oxocyclohex-3-ene-1-carboxylate derivatives (6a-g). Reaction of (6a-c) with lithium diisopropylamide afforded methyl 3-methoxy-5-oxobicyclo[4.2.0]oct-3-ene- 1-carboxylate (2a), methyl 5-methoxy-7-oxo-1,2,3,4,7,7a-hexahydro-3aH-indene-3a-carboxylate (2b) and methyl 6-methoxy-8-oxo-1,3,4,5,8,8a-hexahydronaphtha1ene-4a(2 H)- carboxylate (2c), respectively. Compounds (2b) and (2c) were also obtained from the reaction of (6f) and (6g) with lithium diisopropylamide . Compounds (2a) and (2b) were each obtained as a single bridgehead isomer, the relative stereochemistry of ring fusion of which was assigned as cis on the basis of semiempirical molecular orbital calculations. Compound (2c) was obtained as a mixture of cis-and trans-fused bridgehead isomers. The ester (2b) was converted into the herbicide methyl 5,7-dioxo-6-[1-[(prop-2-enyloxy) imino ] butyl]octahydro-3aH-indene-3a-carboxylate (3a).